Unitary heat exchange and particle collecting apparatus for combustion gases



Feb. 2, 1954 Filed Feb. 24, 1951 R. A. EKSTROM, JR UNITARY HEAT EXCHANGE AND. PARTICLE COLLECTING APPARATUS FOR COMBUSTION GASES l0 Sheets-Sheet 1 INVENTOR. R gner Q. Eksfr0m,Jr:

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Feb. 2, 1954 Filed Feb. 24, 1951 R. A. EKSTROM UNITARY HEAT EXCHANGE AND PAR JR TICLE COLLECTING APPARATUS FOR COMBUSTION GASES 10 sheets-Shea; 2

1N VEN TOR. R gner a. Eksiromfl Feb. 2, 1954 R. A. EKSTROM, JR ,66

UNITARY HEAT EXCHANGE AND PARTICLE COLLECTING APPARATUS FOR COMBUSTION GASES IO SheetS-Sheet 3 Filed Feb. 24, 1951 4 INVE TOR. Ragnar ai immi- Feb. 2, 1954 R. A. EKSTROM, JR 2,667,941

UNITARY HEAT EXCHANGE AND PARTICLE COLLECTING APPARATUS FOR COMBUSTION GASES 1Q- Sheets-Sheet 4 Filed Feb. 24, 1.951

wbrrrrlmrm INVENTOR. Reamer Q1. Eksimm Feb. 2, 1954 R. A. EKSTROM, JR 2,667,941

UNITARY HEAT EXCHANGE AND PARTICLE COLLECTING APPARATUS FOR COMBUSTION GASES Filed Feb. 24, 1951 10 Sheets-Sheet 5 i IN VEN TOR.

F 2, 1954 R. A. EKSTROM, JR 2,6 1

UNITARY HEAT EXCHANGE AND PARTICLE COLLECTING APPARATUS FOR COMBUSTION GASES Filed Feb. 24, 1951 10 Sheets-Sheet e,

a I W" 90 19 16 1/? V f a l F 69 INVENTOR. R13 2? er 0. E kslromJr: IIOV R. A. EKSTROM, JR 2,667,941 UNITARY HEAT EXCHANGE ANB PARTICLE COLLECTING APPARATUS FOR COMBUSTION GASES 10-Sheets-Sheet 7 Feb. 2, 1954 Filed Feb. 24, 1.951

To Capo/q lg"? I N VEN TOR. v Pejner Q. fl smmyn Feb. 2, 1954 R. A. EKSTROM, JR ,6

UNITARY HEAT EXCHANGE AND PARTICLE COLLECTING APPARATUS FOR COMBUSTION GASES l0 Sheets-Sheet 8 Filed Feb. 24, 1951 INVENTOR. Ra ner a. Ekstro j Feb. 2, 1954 R. A. KSTRO 2,667,941

UNITARY HEAT EXCHAN E AND PART OLE COLLECTING APPARATUS FOR COMBUSTION GASES Filed Feb. 24, 1951 1o.s r 1 g ,sneet 9 IZZ ' INVENTOR. Higher aEksarom Jn 2, 1954 R A'. EKSTROM JR 2,6 ,9 1

UNITARY HEAT EXCHANGE AND PAR TICLE COLLECTING. APPARATUS FOR COMBUSTION GASES Filed Feb. 24, 1951' v 10 sneak-snot 10 ti g-5 llllllllllll-lh M lllIl INVENTOKI Pggne d'EkstromJn QM VZHZQ Patented Feb. 2, 1954 UNITARY HEAT EXCHANGE AND PARTICLE COLLECTING APPARATUS FOR COMBUS- TION GASES Regner A.

Application February 24, 1951, Serial No.

6 Claims.

This invention relates to furnaces and particularly those furnaces known as Cupolas and will be described with relation thereto; and also relates to means for utilizing the heat of the gases of combustion and removing materials such as dust, fumes, smoke and ash or gases therefrom.

The objects of the invention are to provide an improved furnace or cupola; to provide an improved means for treating the gases of combustion of cupolas or the like; to provide means for more perfect furnace combustion and more efficient operation; to provide means for utilizing the heat from the discharge gases to heat the air supply to the cupola; to provide for cooling the gas and then removing the dust, smoke or other material therefrom by means of a suitable precipitator or separator; to provide a cupola with a closed combustion chamber and an auxiliary combustion chamber with cooling and washing means and using the heat from the discharge gases to heat the air for supplying the to provide a cupola with means for coolin the discharge gases and with an electronic precipitator or other form of dust collector; to provide means for preventing air polution from furnaces; and to provide such other objects and advantages as will appear more fully hereinafter.

In the accompanying drawings illustrating this invention,

Fig. 1 is a side view of my improved apparatus with parts broken away to show the interior construction;

Fig. 2 is a top plan view of the apparatus shown in Fig. 1 also with parts broken away or omitted for convenience in illustration;

Fig. 3 is a vertical sectional view of the device for cooling the exhaust gases, heating the air supply for the cupola and electrical precipitator;

Fig. 4 is a sectional detail taken substantially on the line 5-4 of Fig. 1;

Fig. 5 is a sectional detail taken on the line of Fig. 1;

Fig. 6 is a section taken Fig. 5;

Fig. 7 is a view similar to Fig. 6 with shown in changing position;

Fig. 8 is an enlarged horizontal sectional view taken substantially on the line 3-8 of Fig. 1;

Fig. 9 is a perspective view of the collecting plates of the electrical precipitator;

Fig. 10 is an enlarged sectional view taken on the line Iii-4B of Fig. 1 showing the grouping of the electric wires in the sections of the precipitator;

on the line 6-45 of the doors Ekstrom, Jr., Harvey, Ill.

Fig. 11 is an enlarged sectional view taken on the line l|--ll of Fig. 1;

Fig. 12 is a similar sectional detail taken on the line 12-42 of Fig. 1;

Fig. 13 is an enlarged sectional view taken on the line Iii-13 of Fig. 1;

Fig. 14 is a section Fig. 13 showing the means precipitating plates;

Fig. 15 is a detail of an expansion joint in one of the shells;

Fig. 16 is a wiring diagram to show the operations of the electric devices of the apparatus;

Fig. 17 is a vertical sectional view of a modification showing a gas cooling and air heating apparatus with a separately mounted electroprecipitator;

Fig. 18 is an enlarged section taken on the line l8-l8 of Fig. 1'7;

Fig. 19 is an en arged plan view of the apparatus shown in Fig. 17;

Fig. 20 is a diagrammatic view showing a further modification of the apparatus;

Fig. 21 is a further modification in which the gases of combustion are first cleaned and cooled and then passed through filter bags to atmosphere;

Fig. 22 is a plan view of Fig. 21;

Fig. 23 is a side view of a group of separator bags showing the intake and also showing means for shaking the bags;

Fig. 2a is an enlarged sectional detail of one of the separator bags.

Fig. 25 is a fragmentary cover '5 showing the means same;

Fig. 26 is a sectional detail showing the supply wires and means for mounting the same;

Fig. 27 is a similar view showing the main wires and also sectional supply wires.

The furnace l as shown in these drawings may which fuel is burned or power or for other purposes, intended to illustrate F. a foundry cupola for melting iron. My improvements may be applied to a single cupola onto a plurality of cupolas, two of which I and 1a are shown in Fig. 1 as connected to a common discharge gas treating apparatus. However, as these cupolas are duplicates, it will only be necessary to describe one of them. This cupola has the usual wind box 2 which may be connected to the tuyeres 3 by downcomer pipes 4 and is also provided with the usual discharge outlet common to such cupolas. However, one of the important for suspending the detail of the cupola for supporting the taken on the line 14-45 of features of the invention consists in providing the cupola which will prevent explosion, and preferably has a shot seal around the edge.

The charging opening is is controlled by doors I and 8' which" are "particularly shown in Figs. 5, 6 and '1. These doors are mounted on vertical pivots or hinges and may be urged to closing position by means of springs Q or gravity. adapted to swing inwardly when the. charging is connected by a of a drum Hi best valve as shown in Fig. 4- which may be actuated a cable I 6- running over guide sheaves i? to any convenient point for manual operation.

may be supported on posts.

The disc 21' of downwardly extending tubes 23, of which are header 24 (see Fig.

lower chamber the cylinder 25.

extends down through the heat exchange apparatus as shown in Fig. 3 and is air from a fan or through pipe 33 as shown in Fig. l. The pipe 3| extends through a series of baflie plates or discs 34 and 35 which are spaced apart with increasing The discs 34 fit closely around the pipe 3i and terminate at a short distance from the inner wall of the cylinder 25, and all the baffle plates are provided with holes for the tubes 23 as shown. The baffle plates 35 fit; closely in the cylinder 25 and have annular openings 36 around the pipe 3!. The pipe 3! fitsin the lowermost baflile plate 34 which is positioned a short distance above the: head They are also forms a header for a plurality 24, thus leaving a and out from the to the cupola thenin operation.

The airpipe 3l has slots 40 leading into the upper chamber 29 so that a limited amount of air may pass from the pipe through the chamber which is connected to pipe 37 by a connecting pipe ii, these slots being controlled by a rotary damper 41a actuated by a rod and crank 4| b and locked by a pin 440..

I provide the novel form of electric precipitator which is connected with and coacts with the heat transfer app ratus. For this purpose, a cylinder or shell 4-2 is mounted concentric with the cylinder 25 and may be supported by means of eye beams 43 forming a part of building or in any other suitable manner.

4% may be supported by beams 48- or in any other suitable manner. The lower end of the shell 42 is closed by a conical ashreceiving member 49 which is secured thereto by bolts and which has will presently be explained.

The gas chamber of sections 52 11 and 12.

plate by means of bolts 65, these bolts furnishing electrical connections to the plates. The collecting plates or electrodes extend down to approximately the level of the head 24.

One set of ionizing electrodes or wires 66 are mounted in the outer peripheral row of passageways 64 and coact with the adjacent plates 6|. These wires extend up through the plate 46 and are supported by insulators 51. Another series of similar wires or electrodes 68 are mounted in the inner peripheral series of openings or passageways $4 and also coact with the adjacent plates. The upper ends of these wires are connected together and current is supplied thereto from any suitable source through wire 59. The lower ends of the wires 66 and 58 extend below the head 24 and are connected through insulators It and "H with a ring 12 preferably of angular cross section. Rapping rods 13 are connected to the outer flange of the ring 12 and extend out through the shell 12 being insulated therefrom by insulators M. It will be understood that the discharge electrodes or wires and the collecting electrodes or plates are properly proportioned and supplied with the right amount of high tension current in order to ionize the particles in the gases and cause them to collect on the plates as is usual with such electrical precipitators.

The cylindrical members or drums erably provided with expansion joints I5 as shown in Fig. 15 which will prevent undue strain incident to changes in the temperatures or heating of the respective members.

Where particularly accurate control of the combustion in the cupola is desired, the downcomer pipes may be provided with automatically controlled gates 16 for regulating the tuyeres air, the action of which will be readily understood.

It is necessary at times to rap the collector plates 0| in order to dislodge any material collected thereon.

The gases of combustion from the cupola I pass through the conduit I3 into the drum IA and then down through the tubes 23 into the space at the bottom of the cylinder 25 below the partition 2G, thence out at the open bottom of the cylinder 25 and up through the passageways es. s ageways, the particulate matter and any other ionizable contents of the gas will become ionized and collect on the plates. The gases then pass out through the peripheral openings 54 into the gas chamber 47 if the gates 55 are open, it being understood that these gates are alternately open and closed by the operating motors 55 and connected parts. The gases having been substantially cleaned or purified, then pass out to the atmosphere through the outlet 59.

In order to remove the collected material from the plates BI, each plate has lugs or projections ll which extend out through the shell 42 and are connected by an arcuate bar i8. As shown in Fig. 8, these arcuate bars are arranged so that they come close together and make a substantially continuous ring around the periphery of the shell.

Any suitable means may be provided for rapping or tapping the plates in order to dislodge material collected thereon, but such means will be described in connection with the means for rapping or tapping of the electrode wire 65. j

The tapping means or hammers may be either pneumatic or electrical. As shown at 19 and are pref As the gases move up through these pasr' the track rail 83.

80, they are electrically operated and may be of either the motor type or solenoids such as commonly used for this purpose. These hammers are mounted on a car or carriage M which travels on a circular track around the precipitator consisting of an upper rail 82 which is T-shaped in cross section, and a lower rail 83 of angular cross section as shown in Fig. 3. The carriage is actuated by a motor 84 having driving connections for turning the driving and supporting wheels 85, Fig. 8. The carriage also has lower guide wheels 86 which engage with The arrangement is such that the upper hammer I9 engages with the bars 18 as it moves in a step by step movement around the precipitator. This movement is best illustrated by the wiring diagram Fig. 16 which also shows the operation of other electro-motive features of the apparatus.

Supply wires 81 and 83 lead from any suitable source of supply as for instance one delivering 110 volts and the current of these wires is controlled by a switch 89. Branch wires 90 and @I lead to the several transformers 92, all of which are adapted to supply the proper high tension current which may be from 15,000 to 100,000 volts or over depending upon the nature of the operation to be performed. The wires 9c are each provided with a switch 93, each of which is actuated by one of the respective gates 55, the arrangement being such that when the gate is up, such switch will be opened and current will be cut off from the transformer which supplies current to the ionizing electrodes '66 through wires 69 of the corresponding section with which such gate is connected.

A wire 94 leads from wire 81 to a contact supply ring 95. Wire 96 leads from wire 88 to a second contact supply ring 91. Current is supplied to the motor 84 from wires and 91 through wipers or brushes 98 and 99 which are mounted on the car frame 8| and arranged to contact said supply wires. Wires I00 and IN lead from the wipers to the terminals of the motor 84.

The supply rings 95 and 91 are carried on a circular insulating block I02 mounted on the rail 82 as shown particularly in Figs. 26 and 27. The block I02 also carries a plurality of segmental wires as shown in Fig. 16 for supplying current to various instrumentalities of the system.

The precipitation system is divided into six sections and the arrangement is such that the gases may be cut off of one section while the rappers or hammers are being actuated to remove the material from the plates in such section. As soon as the material is removed, the gate to the corresponding section is again closed and the current cut off from the hammers. During this period, current is also cut off from the electrode wires 56. The several circuits for supplying and cutting off the current for performing these operations are shown more particularly in Fig. 16.

The wipers 98 and 99 are each divided into two sections as shown, some of which make intermittent contact but one of the wipers is always in contact with the wire 95 and the other with the wire 91.

It will be noted that one of the switches 93 is shown as being open which is accomplished by the gate 55. Current for the motor 53 for such gate is supplied through wire I03 from a segmental contact ring member I04 and from a second contact ring member I05. When the attach bifurca d w pers. 9. and pa s se egme ts, one or the wiper sections will make contactwith thesegment I andthe other wiper segment will make contact with the segment I64, thus closing the circuit through the corresponding motor 56 and; causing it to raise; the gate 55 and open the Switch 93. It will be noted that similar action takes place as the wipers move around the contact circles. The motor 55 is of thev reversible type and when the wipers. 93 and 99 reach the end of the adjacent section, they make contact with suitable segmental contact members and the main rings to reverse the current through the. motor and close the gate. This is done by means of wires I05 and I9? which are connected with the contact members I84 and I05 respectively and with other contact members I08 and IE9 adjacent to the end of the next section as will be seen from Fig. 16. As all of the transformers and motors of the several sections operate in the same manner, further description of the circuits does not appear necessary, but will be readily understood.

The car 8I also carries two wipers or contact shoes Hi! and HI which make contact with seg mental supply wires H2 and H3 and supply curre t to the rappers I9 and 8.9 respectively through wires H 3 and N5, the arrangement being such that the rappers are actuated only when the electric circuit is cut off from the transformers in the respective sections.

A vibrator I I6 is supplied with electricity from the wires 8'! and 88 through wires Ill and H8 such vibrator being preferably continuously actuated during the operation of the apparatus.

The operation of the apparatus will be understood from the above description, but particular attention is called to the provision of a combustion chamber at the top of the cupola instead of permitting the gases of combustion to pass directly into the air. As particularly shown in Fig. l, the upper end of the cupola is formed into a combustion chamber II which leads directly into the conduit I3 and from thence into the drum I4 so that these connected areas all coact to provide for complete combustion of the combustible matter in the gases from the cupola. Such combustion is promoted by suitable gas jets or the like I2.

I have also found it desirable to cool the gases of combustion before attempting to separate the dirt therefrom. For this purpose, the gases are carried down through the tubes 23 and thence through the spray chamber and up through the electronic separation area and finally permitted to escape to atmosphere. At the same time, cold air is drawn through the pipe SI and a controlled amount of such air is permitted to escape through the damper lii which serves to cool the upper ends of the tubes and prevent undue burn-. in or deterioration of the same. The rest of the air comes down as shown and comes up around the tubes and becomes heated and is joined by the air released through the damper and passes to the cupola through the pipe 31. This provides the tuyeres with the air which is sufficiently heated to promote combustion and thus tends to economize the operation of the apparatus. The washing or spraying of the heated gases by means of the water spray 52 not only tends to cool the gases, but humidifies the same which assist in the operation of the electric precipitator.

When two cupolas are connected to a single separating unit as shown in Fig. 1, it will be unders ood hat. on y: due f uch un ts. will he migrated at a ime. h s i in pport nity n repair or take care of the other cupola.

Particular attention is also called to. thenoyel collector. plates which furnish large areas. and provide for vertical chambers for the. respective Wires.

Thetemperature of the gases to be treated may vary greatly, but as, an example, the. ordinary temperature. of the hot gas from a cupola will be approximately 180,0" F. This is. reduced the heat exchanger to. approximately 700 F. and a ain reduced by. the. water spray to approxie mately 35.0 F.

One of he m crt n u da ent l fe tu es of my improvedmethod consists in cooling the hot gases and preferably spraying the same, the air used in cooling being utilized for operating the cupol and then separating or precipitating the dust, smoke, or the like by any suitable means such as the electric precipitator above described or by m ans of strainers'or filters or collecting bags. While the apparatus described makes a compact system for the purposes, it will be noted that the cooling means may be made separate from the dust separating means while still embodying the principles above enumerated.

As illustrating schematically such a system, I have shown in Fig. 20 a cupola I I9 which is connected to cooling means IZil by duct IZI, The cooler is connected to a strainer 0r filter apparatus I22 by duct I23. The gases of combustion after being cooled and filtered are then disc charged to atmosphere through pipe I24.

This illustrates the basic principles above set I forth without showing any particular details of construction. However, in Figs. 17, 18 and 19, I have shown the heat, transfer apparatus I25 in detail, this being substantially the same as that heretofore described so that detail description is not necessary; however, it is noted that this apparatus provides means for cooling gases of combustion while heating the air which enters through the pipe. I26 and passes to the cupola through pipe I27. In this instance, the gases of combustion pass through pipe I28 into the conical discharge section I29 of the electronic precipitator I36. In this case, the body or casing I3I is made rectangular as shown in Fig. 18. The collector plates I32 extend substantially across a casing and are provided with a plurality of fins I33 which are arranged so that the adjacent plates and the fins thereon form rectangular passageways I34 in which the high tension wires I35 are suspended. The. collector plates are carried from supports at the top of the casing and terminate a short distance, above the bottom as shown. The high tension wires I35 are carried by insulators I36 on a plate I31 at the top of the casing I3I. These are all connected together and supplied with high tension current through wire I38 which passes through an insulator I 39 inthe hood I40 at the top of the casing. The lower ends of the wires are connected to a plate or plates I4 I. The discharge gases pass out from the top of the. casing through pipe I42 to atmosphere.

As shown in Fig. 18, the fins or flanges I33 on the ends fo the plates are provided with lugs or projections I43 which extend out through the casing and are connected bybars I44 which bars are arranged in horizontal alignmentv with their ends close together and serve as hammer engagim m ans o jar ing h col c or lates? Any sui bl m anssu h as an, lectr c hammer I45 may be used for this purpose. This hammer is shown as being mounted on a carriage I46 mounted on tracks Id! and I48 and driven by means of a motor drive I49. The carriage Hi6 also carries a second hammer I56 which coacts with rapping pins II on the wire connector It I. With this arrangement, the car is intended to be driven across the side of the stack and then reversed and the hammers actuated to engage with .the coacting parts on the plates and wires.

Automatic control means may be provided for these operations but such means are not shown. It will be seen that with this apparatus, the cooled and humidified gases are passed into the electric precipitator which is particularly efficient in separating different materials such as dust or the like or fumes therefrom.

, In Figs. 21 to 24, I have shown a modified form of apparatus which however, embodies the prin ciple of first cooling and humidifying the gases of combustion as they come from the cupola and.

finally separating the dust therefrom. In this apparatus, the hot gases pass from the cupola I52 to connecting pipe I53 to a downcomer pipe I5 3 which leads to a settling tank I55. The water spray IE6 is mounted in the pipe :55 preferably adjacent to the top thereof and serves to cool and humidify the gases passing through the pipe. Any dirt or dust which may be collected in the tank I55 may be drawn oil" or removed by any suitable means. The pipe I545 is connected by means of pipe I51 with a trough or V-shaped chamber I58 which is also provided at the lower extremity with outlet means I58 for removing dirt or the like. A series of U-shaped tubes Ids connect the chamber I53 with one side of a similar V-shaped connecting trough or chamber I6I. The upper ends of the U-shaped pipes are preferably made with sharp connections to prevent collection of dust at the bends.

Another series of tubes I62 connect the chamber I6I with a similar chamber I63 which in turn is connected by tubes IS E with another chamber I65. This connected system of tubes and chambers provide a large area of cooling surfaces so that the gases are cooled by the air surrounding these parts. The gases are drawn through this system by a fan or pump I66 which is connected by pipe IS! with the last chamber I65. The gases are then driven through a system of collector bags or filters for performing the final cleaning operation. Any number of these bags may be used. In the present instance, the gases are driven through a pipe I58 to an enlarged pipe or drum I69. This drum is connected by means of pipes III] with a series of V-shaped troughs or chambers III which supply gas to the bag filters I12. These filters comprise tubes of any desired diameter as from 6 to 30 inches and may be of any length as from 6 to 30 feet long. They are suspended from overhead tracks H3 and their lower open ends are fastened and connected to the gas inlet headers III as shown. The headers I'II have upwardly extending nipples lI- l over which the lower ends of the bags are mounted as shown in Fig. 24. The nipples are provided with beads I15 to prevent cutting or injury to the bags which may be made of any suitable material but preferably of glass cloth commonly used for this purpose. The ends are held on the nipples by means of clamps lit, the upper ends of which are also beaded. The upper ends of the bags fit over flanges ill on cup-shaped closures I18 and are held thereon by clamps I79. Hanger rods I80 are connected to the closures and are provided at their upper ends with wheels I8I. which ride on the tracks I'I3. It is necessary to shake these bags occasionally to dislodge material collected therein. For this purpose, each series of bags has their hanger rods I83 connected by a longitudinal bar 332 which is reciprocated by means of a crank its and link I84 driven by any suitable source of power. The inlet headers III are provided with outlet openings or discharge means I85 for removing material discharged therein from the bags. A valve I83 provides means for shutting oii gases from the bags when they are to be shaken.

In this form of the apparatus, the hot gases are humidified and are cooled by the heat exchange system which provides for air cooling so that the gases finally pass to the filter bags in a sufficiently cooled condition for the filtering action and without injury to the bags. It will be noted that the area of the passageways are gradually increased until the gas will have comparatively low velocity when passing through the bags and the clean air to the atmosphere.

It will be noted that changes maybe made in the details or" construction of my improved apparatus and in the arrangement of the parts to adapt the same for different purposes, and therefore I do not wish to be limited to the particular construction shown and described except as set forth in the following claims in which I claim:

1. A unitary heat exchange and particle collecting apparatus suitable for cooling and purifying the combustion gases from a cupola, which comprises, in combination, a drum having connected therewith a gas inlet duct, a cap having sealed relation with the top of the drum, a plate forming the bottom of the drum, a plurality of hot blast tubes extending downwardly from the plate, a header in which the lower ends of the tubes are fastened, a cylinder around the tubes and extending below the lower ends thereof, said header forming a partition in the cylinder, a shell around the cylinder forming an annular space therebetween, a discharge hopper for the shell, an outlet for the hopper, spray means below said header, an annular gas chamber around the top of the shell for receiving gas passing up through said space, an outlet from the gas chamber to atmosphere, electric precipitator means positioned in the annular space between the cylinder and the shell including collector plates and electrode wires, means for supplying current to the wires, means for rapping the plates and the wires to discharge material collected thereon, an air inlet pipe extending centrally down through the drum and cylinder and terminating above the bottom thereof, a plurality of baffle plates between the air pipe and the cylinder having openings therethrough and forming a tortuous passageway for air passing upwardly through the cylinder, an air chamber at the top of the cylinder for receiving air therefrom, and means for conducting resulting heated air from said chamber.

2. An apparatus, as in claim 1, having manually controllable means for diverting a portion or the incoming air to the upper portion of said cylinder whereby to cool the upper ends of the tubes and means conducting such air from said cylinder.

3. An apparatus, as in claim 1, further characterized in that the annular shaped electric precipitator chamber is divided into a plurality of sections, lower gas inlet means extending below said sections and below the lower end of said cylinder for conducting gases of combustion to 151 the sections," valving means between said sections and said annular gas chamber for shute ting off the gases at times from the respective sections, and means connecting to the side of said shell for automatically rapping the collector plates in said sections.

4. The apparatus of claim 1 further characterized in that said electric precipitator has the annular gas receiving chamber divided into a plurality of sections, an inlet gate for each section, means for automatically actuating said gates for opening and closing the same at predetermined times, vertically arranged collecting plates mounted in said sections, electrode wires positioned adjacent to. the plates, means for rapping the plates and the wires whereby the plates and wires of one section will be rapped when the gas is cut off therefrom, said sections being opened and closed serially around the chamber, and the rapping of the respective sec,- tions being performed while the successive sections are closed.

5. The apparatus of claim 4 further characterized in that in combinationwith the collecting plates of said electric precipitator, there is a carriage mounted adjacent to the precipitator,

rapping devices mounted on the carriage and adapted to coact with the precipitator, means for moving the carriage, and means for actuating the rapping device.

6. A unitary heat exchange and particle cooling apparatus suitable for cooling and purifying the combustion gases from a cupola, which comprises in combination, a closed gas distributing drum having connected therewith a. gas inlet duct, a cap member extending across the top of the drum, a header plate extending across the lower portion of said drum, a plurality of hot gas tubes extending downwardly from saidplate, a secondfheader plate in which the lower ends of the tubes. are fastened, a cylinder extending from thefirst said header around said tubes. and extending below the lower 'endsthereof, withrsai'd second header forming a partition in the cylinder, a shell around the cylinder forming an an-.

nular space therebetween, a discharge hopper connecting to the lower end of said shell, amaterial outlet from the lower portion of'said .hOD-s per, an annular gas chamber around the top ofsaid shell suitable for receiving gas passing up! Wardly through said annular: space, an outlet from said gas chamber, electrical precipitatormeans positioned in said annular space between the cylinder and the shell, said precipitator means including collector plates and electrode.

wires, means. of supplying current to said wires, means for rapping said plates and said wires to dislodge material collected thereon, air inlet means connecting with theinterior of saidrcylinder and the space around said hot gas tubes, and means for conducting resulted heated air from the interior of said cylinder.

'REGNER A. EKSTROM, J R.

References Cited in the file of this patent UNITED STATES PATENTS. 

